Question

Peptide hormones are synthesized from _______. a. amino acids b. proteins c. cholesterol d. nucleic acids

Short answer

Peptide hormones are synthesized from amino acids.

Step-by-step solution

Understand the Context

Peptide hormones are a type of hormone made up of amino acids. They are distinct from steroid hormones, which are derived from cholesterol, and from other molecules like nucleic acids and proteins.

Identify Key Components

Recognize that peptide hormones are specifically built from smaller building blocks called amino acids. This is crucial as proteins, while also composed of amino acids, refer to a larger and more complex level of organization.

Evaluate the Options

Consider the options given: (a) amino acids, (b) proteins, (c) cholesterol, (d) nucleic acids. Eliminate choices that do not describe the direct building blocks of peptide hormones, such as cholesterol or nucleic acids.

Final Selection

Based on understanding that peptide hormones are synthesized from linear chains of amino acids, select the correct answer: amino acids.

Key concepts

Amino Acids

Amino acids are the fundamental building blocks of life. They come together to form proteins, which are crucial for almost all biological processes. Typically, there are 20 different amino acids that are encoded by the universal genetic code. Whenever amino acids link together like beads on a string, they form what is known as a polypeptide chain. Peptide bonds join these amino acids in a specific sequence, and ultimately, these polypeptide chains can fold and modify to form functional proteins.

Specifically, in the context of peptide hormones, amino acids assemble in a precise order to form these vital signaling molecules. They mediate various physiological functions like metabolism, growth, and mood regulation. Without amino acids, the synthesis of peptide hormones would not be possible.

Hormone Synthesis

Hormone synthesis refers to the process by which hormones are produced in the body. Hormones serve as messengers, carrying signals between cells and organs to regulate body processes. They are either synthesized from amino acids, as in peptide hormones, or from cholesterol, as in steroid hormones.

For peptide hormones, synthesis involves: - Transcription and translation in the cell to produce a peptide chain. - The chain undergoes folding and modifications to become active. - Packaging into vesicles to be transported out of the cell. - Release into the bloodstream to reach target tissues and organs.

In contrast, steroid hormones are synthesized through a different pathway involving cholesterol and occur in specific glands like the adrenal gland and gonads. Understanding the routes of hormone synthesis helps in comprehending how the body maintains balance and responds to changes.

Steroid Hormones

Steroid hormones differ significantly from peptide hormones, mainly because they are synthesized from cholesterol rather than amino acids. While peptide hormones are water-soluble and act quickly, steroid hormones are lipid-soluble, allowing them to easily pass through cell membranes.

Once inside the cell, they bind to specific receptors in the cytoplasm or nucleus, influencing gene expression. This ability gives steroid hormones a more extended effect compared to peptide hormones. Examples of steroid hormones include testosterone, estrogen, and cortisol. These hormones play crucial roles in sexual development, metabolism, and stress responses. Understanding the differences between steroid and peptide hormones is essential for differentiating their biological roles and mechanisms of action.

Cholesterol

Cholesterol is not just a dietary component to be cautious about; it is also a vital molecule in the body. It serves as a precursor for the synthesis of all steroid hormones. In essence, without cholesterol, the production of steroid hormones like estrogen and cortisol would be impossible.

The liver produces the majority of the cholesterol required by the body, while some come from dietary sources. Cholesterol is carried in the bloodstream by lipoproteins and is utilized not only in hormone synthesis but also as a component of cell membranes, contributing to their fluidity and integrity.

Balancing cholesterol levels is crucial, as excess cholesterol can lead to plaque formation in arteries, increasing the risk of cardiovascular diseases. Therefore, cholesterol plays a dual role: vital for hormonal functions and cell structures but potentially harmful when out of balance.